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      Abbreviated rules   07/28/2017

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rh2600

Dan Bernasconi Describes The Three AC75 Concepts

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2 hours ago, Terry Hollis said:

I am not so sure about that .. A hydraulic power pack still needs an electric motor to drive it.

It is really a matter of electro hydraulic versus electro mechanical .. Because the final motion is angular rather than linear we are rotating more than 90 degrees so that would make it very messy to use a hydraulic ram.

I tend to favour an electric motor driving a gearbox which has the advantage of efficient energy recovery when the ballasted foils are lowered.

Of course a hydraulic power pack needs a DC motor to drive the pump, said DC motor powered by batteries. But the real issue is reliability. A mechanical canting system would inevitably use a worm-drive system which is highly inefficient and would shite itself under rapid heavy load activation - unless massively oversized, which creates another problem:  weight.

ETNZ have had great success & experience with their in-house and external-partnerships (e.g. Cariboni)in designing and building hydraulic power packs. With cyclors disallowed and crews of 12, 8 grinders can generate more than enough hydraulic power backed up by appropriately-sized accummulators to achieve all they power they need to drive the foils.I think there will be some electric actuators used in some of the non-critical applications. Maybe they'll leave the power source open (except banning diesel or IC engines).

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54 minutes ago, Terry Hollis said:

I think that in an emergency they would just drop the foils to stability or docking mode .. gravity would work just fine.

During flight, the leeward foil will be producing 8000 Kg of lift. If you lose the ability to control it, it would pivot up - not down  - until the boat slowed enough (say to below 10 kts) that the lift being produced was less than the weight of the foil. 

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1 hour ago, Terry Hollis said:

I think that in an emergency they would just drop the foils to stability or docking mode .. gravity would work just fine.

Not if using electro-mechanical actuators with worm drives - they have to be driven forward/reverse.

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Naw, no problem, just tie it in with explosive bolts, see, solved.

8 minutes ago, Indio said:

Not if using electro-mechanical actuators with worm drives - they have to be driven forward/reverse.

 

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11 minutes ago, animeproblem said:

Naw, no problem, just tie it in with explosive bolts, see, solved.

 

True - 'til Fauth accidentally leans on the emergency button during  manoeuvres  B)

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1 hour ago, ~Stingray~ said:

’It looks like it is about to come out of the water, crawl up the beach and lay eggs.’

Yep, they can extend the legs and stow the boats in drying berths. Think of the space that'll save in the marina. Of course, the wings may stick in the mud but there's an expensive technology they can develop that'll take care of that. No worries. Good as gold, mate.

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1 hour ago, Indio said:

Of course a hydraulic power pack needs a DC motor to drive the pump, said DC motor powered by batteries. But the real issue is reliability. A mechanical canting system would inevitably use a worm-drive system which is highly inefficient and would shite itself under rapid heavy load activation - unless massively oversized, which creates another problem:  weight.

ETNZ have had great success & experience with their in-house and external-partnerships (e.g. Cariboni)in designing and building hydraulic power packs. With cyclors disallowed and crews of 12, 8 grinders can generate more than enough hydraulic power backed up by appropriately-sized accummulators to achieve all they power they need to drive the foils.I think there will be some electric actuators used in some of the non-critical applications. Maybe they'll leave the power source open (except banning diesel or IC engines).

If I was designing an electro mechanical system to operate the ballasted foils I would not consider a worm drive because of it's inefficiency.

There are various solutions to the problem but I envisage a quadrant gear and pinion coupled to a geared motor fitted with a spring loaded caliper brake such as frequently found on warehouse and factory cranes.

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1 hour ago, Indio said:

Not if using electro-mechanical actuators with worm drives - they have to be driven forward/reverse.

No engineer with experience in designing lifting mechanisms would consider using a worm drive for this application.

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On 30/11/2017 at 11:20 AM, Nauti Buoy said:

Ah, yes, the virtual diamond exclusion zone measured by GPS systems. Part of the grand trickle down vision by GD. 

As Dan said, they're already using GPS in some regattas to control OCS rulings, which are a nightmare to call otherwise.. 

It makes sense to me that simple GPS on boats could help decide a lot of penalty situations on the water without the agony of jury rooms and hearsay. 

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1 hour ago, waterboy42 said:

As Dan said, they're already using GPS in some regattas to control OCS rulings, which are a nightmare to call otherwise.. 

It makes sense to me that simple GPS on boats could help decide a lot of penalty situations on the water without the agony of jury rooms and hearsay. 

Well for this one I thought force fields were rather obvious.

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2 hours ago, surfsailor said:

During flight, the leeward foil will be producing 8000 Kg of lift.… 

Lift will be controlled by a flap, quite likely it can develop downforce. If everything fails to the extent that flap control is also lost, hopefully the failsafe is to remove all control so it just goes "flaps up", significantly reducing (perhaps virtually eliminating) lift.

Not fun dropping off foils at 30 kn with zero control. In any case, if the foil arm is free wheeling, it won't offer any RM until it reaches the limit of its travel.

Maybe it needs a Saturn V escape rocket on the top of the mast. When it all goes to shit, all the chainplates explode and a rocket deploys from the top of the mast, lifting the rig clear and gently depositing it in the rigging area.

Apollo_Pad_Abort_Test_-2.jpg

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4 hours ago, Indio said:

Of course a hydraulic power pack needs a DC motor to drive the pump, said DC motor powered by batteries. But the real issue is reliability. A mechanical canting system would inevitably use a worm-drive system which is highly inefficient and would shite itself under rapid heavy load activation - unless massively oversized, which creates another problem:  weight.

ETNZ have had great success & experience with their in-house and external-partnerships (e.g. Cariboni)in designing and building hydraulic power packs. With cyclors disallowed and crews of 12, 8 grinders can generate more than enough hydraulic power backed up by appropriately-sized accummulators to achieve all they power they need to drive the foils.I think there will be some electric actuators used in some of the non-critical applications. Maybe they'll leave the power source open (except banning diesel or IC engines).

How about a pivoting ball screw system

 

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11 minutes ago, dachopper said:

How about a pivoting ball screw system

 

Hahaha..it'll be subject to the same power:weight deficiencies versus hydraulics. Plus the additional problem of heat dissipation - recirculating ball-screws generate a lot of heat.

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I'm no expert in control mechanisms, so it I'm trying to picture what a possible overview of the boat control systems might look like and what will be electric vs hydraulic, or even manual. 

I assumed AC75 grinders will still be charging a hydraulic accumulator, like the AC50 system (except for lifting foils) and the winches will be hydraulic drive? 

If it's not like this, what are the alternatives? Geared direct drive systems and dedicated pedestals, or still just a hydraulic direct drive system with no stored energy (i.e. no accumulator)?

If it's hydraulic + accumulator they can charge the system independently of performing an immediate trimming function, but that could be back to a hamster type function for grinders. 

Are Elevator & Wing trim tabs likely to cable controlled? Servo or stepper motor? Worm drive & control rod (like moth)? Hydraulic? Other? 

Apart from the boats electronics, and maybe some foil trim control systems, the battery on the boat will be used to power a discrete foil lift system containing an electric motor either to direct drive the foil lift or to what? power a hydraulic pump that then powers a hydraulic motor? Therefore, how do you gain benefit adding a hydraulic pump & motor into the system, aren't you just adding mechanical efficiency losses and maybe losing a method for energy regeneration? 

Terry believes the foil lift range of motion is too great for a canting keel style ram + lever operation (I measure it at approx 140 degree range). 

With 140 deg range, I presume that's one reason why they have the foil pivot bearing higher on the freeboard of the hull, so an internal lever arm can rotate past 90 deg. So what drives it? Opposing hydraulic rams are usually used on canting keels. What are alternatives? Curved Rack & pinion?

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This single-cylinder canting configuration can provide lift of the WW foil efficiently and can be constantly auto-adjusted for maximum RM as needed - and they can go with a double-cylinder option for redundancy.

I can see a CNC-machined jig of the canting foils structure for correct alignment of bulkheads and correct installation of the canting mechanism being a One-Design piece of gear under the AC75 Class Rule.

 

image.png.785fc8549189cd635af93128f11379a6.png

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6 minutes ago, Indio said:

This single-cylinder canting configuration can provide lift of the WW foil efficiently and can be constantly auto-adjusted for maximum RM as needed - and they can go with a double-cylinder option for redundancy.

I can see a CNC-machined jig of the canting foils structure for correct alignment of bulkheads and correct installation of the canting mechanism being a One-Design piece of gear under the AC75 Class Rule.

 

image.png.785fc8549189cd635af93128f11379a6.png

With that system there will need to be a tank full of oil plus hydraulic pump flexible hoses on top of the electric motor and battery.

A system like that would not work well for energy recovery when lowering the ballast unless you also added accumulators.

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27 minutes ago, Terry Hollis said:

With that system there will need to be a tank full of oil plus hydraulic pump flexible hoses on top of the electric motor and battery.

A system like that would not work well for energy recovery when lowering the ballast unless you also added accumulators.

Yeah, good system, especially with single but double acting cylinders. 

Correct me if I'm wrong, but can't you potentially use the downforce when dropping the foil to turn the hydraulic pump into a motor which could then reverse the electric motor rotation turning it into a generator (as some can do) and recover charge that way (with some losses)? 

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1 minute ago, waterboy42 said:

Yeah, good system, especially with single but double acting cylinders. 

Correct me if I'm wrong, but can't you potentially use the downforce when dropping the foil to turn the hydraulic pump into a motor which could then reverse the electric motor rotation turning it into a generator (as some can do) and recover charge that way (with some losses)? 

Yes but not as efficient as using a motor generator combined with a mechanical actuator.

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1 minute ago, Terry Hollis said:

Yes but not as efficient as using a motor generator combined with a mechanical actuator.

True 

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47 minutes ago, Terry Hollis said:

With that system there will need to be a tank full of oil plus hydraulic pump flexible hoses on top of the electric motor and battery.

1

Yeeesss..so what's your point? Do you know how compact an integrated DC power pack and controls can be? They can be co-located with the canting hardware!!

Quote

A system like that would not work well for energy recovery when lowering the ballast unless you also added accumulators.

For a potentially 2-hour or less race, what benefits would they gain from regenerative energy recovery, when they can use a bank of Li-Ion marine batteries (24-V-200A/hr-5120Wh/50kgs) to power their entire hydraulics budget, or use 6-8 grinders?

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16 minutes ago, Indio said:

Yeeesss..so what's your point? Do you know how compact an integrated DC power pack and controls can be? They can be co-located with the canting hardware!!

Just the weight of all that oil.

For a potentially 2-hour or less race, what benefits would they gain from regenerative energy recovery, when they can use a bank Li-Ion marine batteries (24-V-200A/hr-5120Wh/50kgs) to power their entire hydraulics budget?

Energy recovery saves more weight.

 

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Interesting that Dan was definitely talking about a hydraulic motor lifting the foils. If it was a ram based operation it would be hydraulic pump driven? 

A hydraulic motor driven pinion attached to the inboard arm of the foil could run around a fixed rack, but I doubt it could take such a load on a small drive area unless multiple pinions

IMG_20171201_191917.png

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2 hours ago, Indio said:

Hahaha..it'll be subject to the same power:weight deficiencies versus hydraulics. Plus the additional problem of heat dissipation - recirculating ball-screws generate a lot of heat.

Heat dissipation.... My CnC machine doesn't seam to think so and it runs for 8 hours continuously moving ?

 

 

Something like this...DA99 Roller Screw Actuator

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9 minutes ago, dachopper said:

Heat dissipation.... My CnC machine doesn't seam to think so and it runs for 8 hours continuously moving ?

How do you have a pivoting ball screw system? I can't picture it. 

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3 minutes ago, waterboy42 said:

How do you have a pivoting ball screw system? I can't picture it. 

Well you could either fix the motor /shaft and ballscrew to the hull, and then have a load arm + cam transfer the linear motion to angular....

 

Or potentially have the motor and ball screw fix directly to the end of the load + pivot point in the hull... hence pivoting not fixed, less parts required.

 

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1 hour ago, Terry Hollis said:

With that system there will need to be a tank full of oil plus hydraulic pump flexible hoses on top of the electric motor and battery.

A system like that would not work well for energy recovery when lowering the ballast unless you also added accumulators.

 

1 hour ago, Indio said:

This single-cylinder canting configuration can provide lift of the WW foil efficiently and can be constantly auto-adjusted for maximum RM as needed - and they can go with a double-cylinder option for redundancy.

I can see a CNC-machined jig of the canting foils structure for correct alignment of bulkheads and correct installation of the canting mechanism being a One-Design piece of gear under the AC75 Class Rule.

 

image.png.785fc8549189cd635af93128f11379a6.png

Terry, what issue do you have with the ram idea and range of motion? Increased force needed at the acute angles at the extents of the travel? 

If range is 140 degree pivot, you have close to 100% force in centre of arc but 20 degree acute angles at either end of arc, needing a heavier more powerful ram etc? 

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14 minutes ago, dachopper said:

Well you could either fix the motor /shaft and ballscrew to the hull, and then have a load arm + cam transfer the linear motion to angular....

 

Or potentially have the motor and ball screw fix directly to the end of the load + pivot point in the hull... hence pivoting not fixed, less parts required.

 

Got you.. Interesting idea! Especially at rapid feed rates.. 

Could be light, fast powerful and accurate, with a good force contact area. 

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51 minutes ago, waterboy42 said:

 

Terry, what issue do you have with the ram idea and range of motion? Increased force needed at the acute angles at the extents of the travel? 

If range is 140 degree pivot, you have close to 100% force in centre of arc but 20 degree acute angles at either end of arc, needing a heavier more powerful ram etc? 

I do not have an issue with hydraulic ram system .. it's just that I think it is heavier and more complex.

I think if they want to use rams it be better with two rams like a V2 engine.

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1 hour ago, Terry Hollis said:

 

Ok..why don't you find an electro-mechanical actuator that would deliver the same force as a 100mm cylinder @ 350bar (28 tonne) and then compare its size and weight with the hydraulic cylinder?

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7 minutes ago, Terry Hollis said:

I do not have an issue with hydraulic ram system .. it's just that I think it is heavier and more complex.

I think if they want to use rams it be better with two rams like a V2 engine.

A 2-cylinder system will provide back-up redundancy if one fails. And they won't be any heavier (probably lighter than) an equivalent electric actuator system - more reliable.

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8 minutes ago, Indio said:

Ok..why don't you find an electro-mechanical actuator that would deliver the same force as a 100mm cylinder @ 350bar (28 tonne) and then compare its size and weight with the hydraulic cylinder?

https://globalaviationaerospace.com/2016/03/13/the-future-of-aircraft-actuators-hydraulic-or-electric-power/

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23 hours ago, Xlot said:

Link al post #205 - Il replay parte ogni ora

Cercavo l'MP3... per ascoltarlo in auto! :-)

Ho risolto convertendo il video direttamente tramite un sito. ;-)

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8 hours ago, Indio said:

No thanks.

5a210f5475371_Rotatingkeelmono....JPG.6028ebf7bbf087709afae51dbe331d5d.JPG

Same boat I though it was the smaller scale :-)
That or Vlad Murnikov's concept. 

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I was out for a fly on a 787 this week, and noticed the new wing design...uptips are gone (thankfully), replaced by a thin wingtip much as the more recent foil designs sported last cycle.

And why not have multiple trim tabs on a foil? Like flaps for low speed lift and trims for control at high speeds? Will we see this?

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The AC isn't about what is simple, cheap or easy to sail. Personally I'm pretty interested to see where the AC75 concept takes us. It's amusing how  discombobulated the cat-boys are by a new idea that doesn't involve two or three hulls.

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7 hours ago, dogwatch said:

 It's amusing how  discombobulated the cat-boys are by a new idea that doesn't involve two or three hulls.

No, cat-boys are interested by a complicated, expensive, slower concept, trad-mono old boys discombobulated by a mono on 3 legs.

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8 hours ago, dogwatch said:

The AC isn't about what is simple, cheap or easy to sail. Personally I'm pretty interested to see where the AC75 concept takes us. It's amusing how  discombobulated the cat-boys are by a new idea that doesn't involve two or three hulls.

Yeah, we don't choose to do the AC and other stuff because they are easy, we choose tho do them because they're hard ;)

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On 11/30/2017 at 3:42 PM, Xlot said:

In fact, if not forbidden by the Rule, it would be advantageous to swing the leeward foil beyond the vertical and to the windward side (the windward foil having already been extended)

Can't they just add another appendage?

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4 hours ago, hoom said:

I feel like I'd have liked to see the other 2 concepts.

Assuming, this one is the 'way out there' one, at least the second option would be worth a look, for sure. We may see it yet.

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On 12/1/2017 at 7:33 PM, dachopper said:

Heat dissipation.... My CnC machine doesn't seam to think so and it runs for 8 hours continuously moving ?

 

 

Something like this...DA99 Roller Screw Actuator

How much force is it applying continuously? 5-10 tonne?

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3 hours ago, dachopper said:

4 Newtons :) the levers do the rest. 

You've just answered why your roller screws won't be used to drive the AC75 foils. The only option is hydraulics. A brief assumption on the forces required to move the foils at the required speed and the frequency of constant adjustments suggest the hydraulic system budget won't be as demanding as the AC50s, so it should be easily powered by the grinders.

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although I on a basic level am excited about this concept, I wonder if they should have a "non-flying" board set for lighter winds to avoid less interesting races where only one boat is flying  

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^ So leave some areas open for development, but handicap anyone who gets a jump?

Yeah, that makes sense....

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8 hours ago, Indio said:

You've just answered why your roller screws won't be used to drive the AC75 foils. The only option is hydraulics. A brief assumption on the forces required to move the foils at the required speed and the frequency of constant adjustments suggest the hydraulic system budget won't be as demanding as the AC50s, so it should be easily powered by the grinders.

IT's not how big it is, it's how you use it.

 

You think this ain't up to the task still???????

 

I think the boat will snap in half first before that thing fails.....

 

Kammerer_Schwerlast_KGT.jpg?itok=LuUfbUY

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^/^^ I don't see why one has to reinvent the wheel. Much quicker looking at catalogs, at first glance this would seem to fit the bill - a bit heavy, but there's plenty more:

http://www.moog.com/content/sites/global/en/products/actuators-servoactuators/defense/military-ground-vehicles-actuators/electromechanical-gun-elevation-actuator-c116l422e.html

 

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6 hours ago, nav said:

^ So leave some areas open for development, but handicap anyone who gets a jump?

Yeah, that makes sense....

Yes, that would of course be the downside. 

 

Maybe only in very unstable conditions.....

 

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1 hour ago, dachopper said:

IT's not how big it is, it's how you use it.

 

You think this ain't up to the task still???????

 

I think the boat will snap in half first before that thing fails.....

 

Kammerer_Schwerlast_KGT.jpg?itok=LuUfbUY

I'm not sure I'm getting the picture 100%, because to pivot and drive the inboard foil lever arm, either the ball screw is captured at the pivot and the shaft rotates, or the shaft is captured and the ball screw rotates. 

The foil has approx 140 deg range of motion and a hydraulic ram works because it telescopes inside its own length, whereas a fixed length shaft would interfere with the hull at the extents of the motion range? 

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1 hour ago, waterboy42 said:

The foil has approx 140 deg range of motion and a hydraulic ram works because it telescopes inside its own length, whereas a fixed length shaft would interfere with the hull at the extents of the motion range? 

True dat :(

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3 hours ago, dachopper said:

IT's not how big it is, it's how you use it.

 

You think this ain't up to the task still???????

 

I think the boat will snap in half first before that thing fails.....

 

Kammerer_Schwerlast_KGT.jpg?itok=LuUfbUY

Weight & Speed = No Roller screws

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Given that Dan has said a hydraulic "motor" will (most probably) drive the foils, its still intriguing what system he's thinking of as you need a pump not a motor to actuate rams right? 

Unless he mixed up his terms...

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^

So we come back to Dan's quote and....

On 29/11/2017 at 9:38 PM, nav said:

Again to clarify, if you have batteries you have electric motors doing the work either way - the difference being whether they cant the foils directly or they pump oil - right?

He only seemed to be thinking of those 2 ^ options - but it's possible an engineer somewhere will suggest another viable option before the rule get's writ'.

Since TE summarily dismissed Stingray and all the "Knuckle-heads" here without posing a question, did Dan clarify 100% that there was only (to his knowledge) to be movement about the cant axis (plus trim-tabs)?

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47 minutes ago, nav said:

^

So we come back to Dan's quote and....

He only seemed to be thinking of those 2 ^ options - but it's possible an engineer somewhere will suggest another viable option before the rule get's writ'.

Since TE summarily dismissed Stingray and all the "Knuckle-heads" here without posing a question, did Dan clarify 100% that there was only (to his knowledge) to be movement about the cant axis (plus trim-tabs)?

Dan: "We're envisaging.. The cant operation will be powered by batteries driving a hydraulic motor, although it's early days.." 
Tom: So Hydraulic Motor not an Electric Motor?"
Dan:  "Well.. I think we'll look at both options, it's an interesting area, traditionally in AC, we've been focused on hydraulics for driving high loads. Electric Motors are moving into that area and it's something we'll look at"
Tom: "it's going to require a lot of torque one way or other right?"
Dan: "for sure... 

 

And yes, no fore / aft main foil canting (too much energy to operate) and trim tabs like ailerons on the wing trailing edge for ride height. 

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2 hours ago, waterboy42 said:

Given that Dan has said a hydraulic "motor" will (most probably) drive the foils, its still intriguing what system he's thinking of as you need a pump not a motor to actuate rams right? 

Unless he mixed up his terms...

Just a simple inadvertent conflation of the two options. Without a solid wing-sail, the hydraulic budget for the AC75 would be significantly less demanding than the AC50s', so they can easily use a bank of batteries to power a DC hydraulic system to operate the foils - or they can use grinders.

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29 minutes ago, Indio said:

Just a simple inadvertent conflation of the two options. Without a solid wing-sail, the hydraulic budget for the AC75 would be significantly less demanding than the AC50s', so they can easily use a bank of batteries to power a DC hydraulic system to operate the foils - or they can use grinders.

OK, makes sense as the compact power units have an integrated electric motor, but act as a hydraulic  pump. 

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The hull and foils are obviously very much a work in progress, as I don't think they can work in their current configuration... 

The images show the foils exiting the hull very close to waterline with fairly square hull sides and bottom. 

The images also show approx. 140 deg range of motion. To move such a mass and long arm they will need some form of inboard lever arm to act on, otherwise the forces required approach infinity as you approach the pivot axis, but the square sides and bottom limit the range of motion to 90 degrees at best.. 

The only way to get greater rotation is to have the pivot bearing higher on the side of the hull 

This pic below seems to show a short lever arm protruding through the starboard side of the hull.. 

unnamed (4)_1511818242232.jpg

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How will they remove the foils? Lift the boat way up high on a travelift, remove the wings from below, then disconnect from the levers and crane lift the arms up through the top?

That’s the Q from me that TE breezed past; maybe I didn’t make the concern clear enough.

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  ^ With the boat 5.3 m wide and 5 m draught, is that within the capability of common travel lifts?

 

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38 minutes ago, ~Stingray~ said:

How will they remove the foils? Lift the boat way up high on a travelift, remove the wings from below, then disconnect from the levers and crane lift the arms up through the top?

That’s the Q from me that TE breezed past; maybe I didn’t make the concern clear enough.

Yeah, I think Tom didn't want to push Dan on finer details as he'd already said they were very much a work in progress.. 

I was assuming the wings would be a custom design element and possibly have light air / heavy air configurations, but I can't see them being quick or easy to swap out... 

Removing the arms up through the hull was my thinking too, but how do you get those 1.5t wings off first...

I doubt they'll want to lift the boats, or they'll have similar cost, time issues as hoisting solid Wing Sails.

Maybe the whole foil assembly will be one design.. 

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1 hour ago, waterboy42 said:

Yeah, I think Tom didn't want to push Dan on finer details as he'd already said they were very much a work in progress.. 

I was assuming the wings would be a custom design element and possibly have light air / heavy air configurations, but I can't see them being quick or easy to swap out... 

Removing the arms up through the hull was my thinking too, but how do you get those 1.5t wings off first...

I doubt they'll want to lift the boats, or they'll have similar cost, time issues as hoisting solid Wing Sails.

Maybe the whole foil assembly will be one design.. 

There was a suggestion somewhere (by RG?) in an early article that the arms would be lifted out the top. Was curious to hear Dan’s more-current thinking.

If the arms are going to be constructed of (was it?) indestructible stainless steel instead of CF then it’s possible the arms won’t need much removal - unless they will not be OD and teams want to try many different configurations.

Since according Dr Dan the canting mechanism (and so probably the entire high-stress foil box as you suggest) likely will be OD then the arms may be OD too, despite my hopes. In either case, perhaps the entire foil assembly could be lifted, arms embedded? Despite the obvious structural/hull implications around making the boxes separate-able from the hull?

Entire aircraft landing gears can be replaced, but geez.. it’s a massive task end-to-end before you’d trust anyone flying aboard with it.

 

 

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This very questionable logistics question is part of my belief of why Govt was wanting a voice in the boat selection way back & why I'm not entirely impressed with the concept.

I foreshadowed I thought sarcastically back then TNZ winding up going 'hey Govt, the boat has a huge footprint now up to you to find a place to fit them or we take The Cup elsewhere'.

 

I'm pretty disappointed that the design they've gone for is a huge footprint boat with huge technical risk/barrier & frankly an un-pretty monstrosity.

I still would prefer a more conventional displacement/semi-foiling ~60foot cat.

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36 minutes ago, hoom said:

This very questionable logistics question is part of my belief of why Govt was wanting a voice in the boat selection way back & why I'm not entirely impressed with the concept.

I foreshadowed I thought sarcastically back then TNZ winding up going 'hey Govt, the boat has a huge footprint now up to you to find a place to fit them or we take The Cup elsewhere'.

 

I'm pretty disappointed that the design they've gone for is a huge footprint boat with huge technical risk/barrier & frankly an un-pretty monstrosity.

I still would prefer a more conventional displacement/semi-foiling ~60foot cat.

When the AC75 is in docking mode it's footprint is a little more than half that of an AC50 .. in fact it is not much different to a 12 metre.

The footprint when it is racing cannot be a problem because their is plenty of room in the gulf.

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Maybe the lever arm pivoting out of the hull, is the bit you attach the crane to, so the foil drops out rather than being dropped into the boat?

 

Or more likely they are fiddling with different concepts, and that bit was just a remnant of some draft config for the foils.

 

If they are trying to make a concept for the masses.... then I go back to my original point ..... If it's too light for them to get out of the water on a single foil then surely submerging both foils, providing twice the lift at lower speed, will get them out and allow them to accelerate. Why would you bother having different sized foils for different winds in that case. In what universe is a consumer going to have several different sized 1.5 tonne foils sitting next to their yacht for use?

The best compromise I can think of, is a slip on shell. In light winds they could slip two halves of a thicker, larger foil on the outside of the weighted versions, but even that seems stupid.

 

Even in The kitefoil world cup , the top riders aren't really bolting on different Main foils..... If they foils are high A/R and thin they do extremely well in the low wind, but get overtaken by the stubbier, thicker foils in the windier stuff.

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They are surely just going to lift them out complete.

They lifted those ridiculously heavy AC90's out so surely these can't be that much of a challenge!

Googling boat travel lifts and looking at images would appear to show a whole slew of machines up to the job...

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17 hours ago, Terry Hollis said:

When the AC75 is in docking mode it's footprint is a little more than half that of an AC50 .. in fact it is not much different to a 12 metre.

Bernasconi (I think) said they need to put it on the hard with both foils out at max-width to take them out.

So basically its taking up as much expensive land area as a 75' cat.

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55 minutes ago, hoom said:

Bernasconi (I think) said they need to put it on the hard with both foils out at max-width to take them out.

So basically its taking up as much expensive land area as a 75' cat.

That is a matter of choice .. They can save on land area and have their boat in a cradle as a normal keel boat or splash out and have it like a multi.

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"Footprint" - as conventionally seen from above - is a bit incomplete here, think 3d.  

Can the draft of this thing be accommodated in all areas it is destined to berth and race?  May be an issue, maybe not.  Don't know.

 

When I look at this boat and think about pre-start maneuvers I visualize two bucks, in rut, with intertwined antlers.

I hope it works for the AC but I think any expectation of trickle-down is unrealistic.

Just my 2 cents.....

Charlie Mayer, aka, "cat-boy"

 

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57 minutes ago, hoom said:

Bernasconi (I think) said they need to put it on the hard with both foils out at max-width to take them out.

So basically its taking up as much expensive land area as a 75' cat.

Actually, that would likely be the quickest and safest way, but they are about 50ft wide x 75ft long in that mode, so how many bases will have that water space capacity... Maybe, if they remove the dock fingers.. 

Interestingly the mock-up AC Village video shows tall mobile cranes on 3 syndicate bases, which may reinforce that this is their plan. 

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1 hour ago, hoom said:

Bernasconi (I think) said they need to put it on the hard with both foils out at max-width to take them out.

So basically its taking up as much expensive land area as a 75' cat.

Do you recall which interview / article that was from? Don't think it was mentioned in the Sailing Illustrated interview with Tom Ehman.

Another one maybe? 

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9 hours ago, dachopper said:

 

If they are trying to make a concept for the masses.... then I go back to my original point ..... If it's too light for them to get out of the water on a single foil then surely submerging both foils, providing twice the lift at lower speed, will get them out and allow them to accelerate. Why would you bother having different sized foils for different winds in that case. In what universe is a consumer going to have several different sized 1.5 tonne foils sitting next to their yacht for use?

The best compromise I can think of, is a slip on shell. In light winds they could slip two halves of a thicker, larger foil on the outside of the weighted versions, but even that seems stupid.

Speculating, but I think lead ballast in the end of one design foil arms, but cnc machined bolt on steel wings would be a great cost saver and still allow the wings to be a box rule design component.

Custom wings could be machined in a week or so rather than months for GRP foils, plus steel is 7.85 specific gravity vs 13.34 lead or GRP 1.60, so still get fairly good ballast 

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1 hour ago, waterboy42 said:

Actually, that would likely be the quickest and safest way, but they are about 50ft wide x 75ft long in that mode, so how many bases will have that water space capacity... Maybe, if they remove the dock fingers.. 

Seems my words were less precise than intended :o

I meant 'to remove the foils from the boat' not 'to haul the boat out of the water'.

 

1 hour ago, waterboy42 said:

Do you recall which interview / article that was from? Don't think it was mentioned in the Sailing Illustrated interview with Tom Ehman.

Pretty sure it was that interview yes.

 

1 hour ago, Charlie P Mayer said:

Can the draft of this thing be accommodated in all areas it is destined to berth and race?  May be an issue, maybe not.  Don't know.

All of the options in the Council documents were going to require dredging to fit the 5.5m draught.

That'd also be an advantage of a more conventional multihull: they'd require only rudder draught.

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If the mock up video is an indicator of ETNZ thinking, then it seems syndicates would have a crane + a cradle set up. 

This zoomed shot shows an ETNZ boat on a high cradle with foils out. They could lift it in mooring mode then cant the foils to a suitable position for wing change / maintenance before dropping on the cradle. 

At Stability mode level, the wings are horizontal, so an easy drop onto a jig & trolley. 

 

IMG_20171206_181139.png

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If the foils are properly articulated, they boats can just walk up the beach like their lizard facsimiles. 

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No time presently to catch up with this thread but is there any rough estimates out there on how much the JC75 is going to cost to develop and build?  

Going off the basic details I know it seems that cost reductions compared to an AC50 program is a farce at this point. Right?

WetHog  :ph34r:

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